AT&T Inc.'s ambitions to expand in Europe have run into unexpected hurdles amid the growing outcry across the region over surveillance by the National Security Agency. German and other European officials said any attempt by AT&T to acquire a major wireless operator would face intense scrutiny, given the company's work with the U.S. agency's data-collection programs.

Resistance to such a deal, voiced by officials in interviews across Europe, suggests the impact of the NSA affair could extend beyond the diplomatic...